U.S. Pat. No. 3,663,667 discloses a process for producing multimetal alloy powders. Thus, multimetal alloy powders are produced by a process wherein an aqueous solution of at least two thermally reducible metallic compounds and water is formed, the solution is atomized into droplets having a droplet size below about 150 microns in a chamber that contains a heated gas whereby discrete solid particles are formed and the particles are thereafter heated in a reducing atmosphere and at temperatures from those sufficient to reduce said metallic compounds to temperatures below the melting point of any of the metals in said alloy.
U.S. Pat. No. 3,909,241 relates to free flowing powders which are produced by feeding agglomerates through a high temperature plasma reactor to cause at least partial melting of the particles and collecting the particles in a cooling chamber containing a protective gaseous atmosphere where the particles are solidified. In this patent the powders are used for plasma coating and the agglomerated raw materials are produced from slurries of metal powders and binders. Both the U.S. Pat. Nos. 3,663,667 and 3,909,241 are assigned to the same assignee as the present invention.
In European Patent Application No. W08402864 published Aug. 2, 1984, also assigned to the assignee of this invention, there is disclosed a process for making ultra-fine powder by directing a stream of molten droplets at a repellent surface whereby the droplets are broken up and repelled and thereafter solidified as described therein. While there is a tendency for spherical particles to be formed after rebounding, it is stated that the molten portion may form elliptical shaped or elongated particles with rounded ends.
Production of copper and copper based alloys powders have also been produced by gas and water atomization of molten ingots of copper or copper alloy. These methods generally produce a relatively large fraction of material above about 20 microns.
As used in this invention the term "copper based" materials or alloys or particles means the foregoing substances which includes copper per se and alloys of copper with one or more additional metals in which copper is the major metal, usually in amounts of greater than 50% by weight.
It is believed therefore that a relatively simple process which enables finely divided metal alloy powders to be hydrometallurgically produced from sources of the individual metals is an advancement in the art.